U.S. patent application number 12/530752 was filed with the patent office on 2010-06-17 for head cover of an internal combustion engine.
Invention is credited to Yoshihiro Akiyama, Isao Emi, Atsushi Yoshimura.
Application Number | 20100147273 12/530752 |
Document ID | / |
Family ID | 40001944 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100147273 |
Kind Code |
A1 |
Akiyama; Yoshihiro ; et
al. |
June 17, 2010 |
HEAD COVER OF AN INTERNAL COMBUSTION ENGINE
Abstract
A part of a ceiling wall (14) of a head cover (10) that opposes
an intake collection chamber (51) is constituted by a concave
ceiling wall (20) that defines a concave surface facing the intake
collection chamber (51), and the concave ceiling wall (20) is
formed with a recessed groove (21) that further recedes toward an
inner side of the head cover.
Inventors: |
Akiyama; Yoshihiro;
(Wako-shi, JP) ; Yoshimura; Atsushi; (Wako-shi,
JP) ; Emi; Isao; (Tokyo, JP) |
Correspondence
Address: |
ARENT FOX LLP
1050 CONNECTICUT AVENUE, N.W., SUITE 400
WASHINGTON
DC
20036
US
|
Family ID: |
40001944 |
Appl. No.: |
12/530752 |
Filed: |
April 30, 2008 |
PCT Filed: |
April 30, 2008 |
PCT NO: |
PCT/JP2008/001122 |
371 Date: |
January 27, 2010 |
Current U.S.
Class: |
123/572 ;
123/195C |
Current CPC
Class: |
F02M 35/10078 20130101;
F02F 7/006 20130101; F01M 13/0416 20130101; F02M 35/10222 20130101;
F02M 35/112 20130101; F02M 35/10111 20130101; F02M 35/10288
20130101 |
Class at
Publication: |
123/572 ;
123/195.C |
International
Class: |
F02B 25/06 20060101
F02B025/06; F02B 77/00 20060101 F02B077/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2007 |
JP |
2007-130263 |
Claims
1. A head cover of an internal combustion engine, comprising a
ceiling wall, wherein an intake collection chamber of an engine
intake system is disposed on an outer side of the ceiling wall and
a breather chamber of a blow-by gas is defined on an inner side of
the ceiling wall, wherein a part of the ceiling wall that opposes
the intake collection chamber is constituted by a concave ceiling
wall having a concave surface facing the intake collection chamber,
and the concave ceiling wall is formed with a recess that recedes
toward an inner side of the head cover.
2. The head cover according to claim 1, where a shape of the
concave surface of the concave ceiling wall is designed so as to
extend substantially along an outer profile of the intake
collection chamber that opposes the concave ceiling wall.
3. The head cover according to claim 1, wherein the recess is
formed at a lowermost part of the concave surface of the concave
ceiling wall.
4. The head cover according to claim 2, wherein the recess is
formed at a lowermost part of the concave surface of the concave
ceiling wall.
5. The head cover according to claim 1, wherein the recess
comprises at least one recessed groove that extends in a direction
along a crankshaft of the internal combustion engine.
6. The head cover according to claim 5, wherein the ceiling wall is
formed with a boss portion which defines an oil inlet and to which
an oil filler cap can be detachably attached, and an oil trap
portion that surrounds the boss portion and has a part formed with
an oil discharge opening, wherein the recessed groove is connected
to the oil trap portion at one end of the recessed groove.
7. The head cover according to claim 1, wherein grid-shaped ribs
are formed on an inner surface of the concave ceiling wall.
Description
TECHNICAL FIELD
[0001] The present invention relates to a head cover of an internal
combustion engine, and particularly relates to a head cover in
which a breather chamber of a blow-by gas is defined on an inner
side of a ceiling wall of the head cover.
BACKGROUND ART
[0002] A head cover attached to a cylinder head of an internal
combustion engine to cover a valve mechanism is sometimes formed
with a breather chamber (breather passage) on an inner side thereof
such that a blow-by gas flows through the breather chamber in order
to have an oil mist contained in the blow-by gas be separated from
the blow-by gas (gas-liquid separation) (see Japanese Patent
Application Laid-Open Publication No. 2005-155475, for
example).
[0003] For the purpose of achieving a compact arrangement of an
intake system of the internal combustion engine, an intake
collection chamber of an intake manifold or a surge tank may be
disposed close to an upper side of the head cover. In such a case,
in order to cope with the requirements for a design change or
volume increase of the intake collection chamber, it is demanded to
reduce the height of the head cover and hence minimize the height
of the breather chamber (passage) defined on the inner side of the
head cover.
[0004] It should be noted in this regard that if the volume of the
breather chamber were insufficient, the performance of the breather
chamber to remove oil mist would decrease, and therefore, it is
necessary to ensure an adequate volume of the breather chamber
while maintaining a small height of the breather chamber in order
to cope with the design change or volume increase of the intake
collection chamber as well as achieve favorable oil mist removing
function. This can be achieved by increasing the size of the
breather chamber of the head cover in a lateral direction (in a
horizontal direction perpendicular to a crankshaft direction of a
longitudinal engine).
[0005] However, the size increase of the breather chamber of the
head cover in the lateral direction can lead to a ceiling wall of
the head cover having a large flat surface, and this can reduce a
panel rigidity of the ceiling wall, which in turn makes the ceiling
wall easier to resonate with vibrations generated by the valve
mechanism and the like on the engine main body side, and thus
deteriorates the performance regarding the vibration and noise
phenomena (NVH performance).
BRIEF SUMMARY OF THE INVENTION
[0006] An object to be achieved by the present invention is to
provide a simple modification of the head cover structure that can
cope with the design change and volume increase of the intake
collection chamber of the engine intake system disposed above the
head cover, while ensuring a sufficient volume of the breather
chamber without deteriorating the NVH performance.
[0007] In order to achieve the above object, the present invention
provides a head cover of an internal combustion engine, comprising
a ceiling wall, wherein an intake collection chamber of an engine
intake system is disposed on an outer side of the ceiling wall and
a breather chamber of a blow-by gas is defined on an inner side of
the ceiling wall, wherein a part of the ceiling wall that opposes
the intake collection chamber is constituted by a concave ceiling
wall having a concave surface facing the intake collection chamber,
and the concave ceiling wall is formed with a recess that recedes
toward an inner side of the head cover.
[0008] In the head cover of an internal combustion engine according
to the present invention, preferably, a shape of the concave
surface of the concave ceiling wall 20 is designed so as to extend
substantially along an outer profile of the intake collection
chamber that opposes the concave ceiling wall.
[0009] In the head cover of an internal combustion engine according
to the present invention, the recess is preferably formed at a
lowermost part of the concave surface of the concave ceiling
wall.
[0010] In the head cover of an internal combustion engine according
to the present invention, the recess preferably comprises at least
one recessed groove that extends in a direction along a crankshaft
of the internal combustion engine.
[0011] In the head cover of an internal combustion engine according
to the present invention, preferably, the ceiling wall is formed
with a boss portion which defines an oil inlet and to which an oil
filler cap can be detachably attached, and an oil trap portion that
surrounds the boss portion and has a part formed with an oil
discharge opening, wherein the recessed groove is connected to the
oil trap portion at one end of the recessed groove.
[0012] The head cover of an internal combustion engine according to
the present invention is preferably provided with grid-shaped ribs
formed on an inner surface of the concave ceiling wall.
[0013] In the head cover of an internal combustion engine according
to the present invention, because the part of the ceiling wall that
opposes the intake collection chamber is constituted by a concave
ceiling wall that defines a concave surface facing the intake
collection chamber, it is possible to reduce the height of the head
cover so that the head cover does not interfere with the intake
collection chamber, while achieving a necessary volume of the
breather chamber. Further, because the concave ceiling wall is
formed with a recessed groove that further recedes toward the inner
side of the head cover, it is possible to improve the panel
rigidity of the concave ceiling wall and prevent deterioration of
NVH performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Now the present invention is described in the following with
reference to the appended drawings, in which:
[0015] FIG. 1 is a longitudinal cross-sectional view showing an
embodiment of a head cover of an internal combustion engine
according to the present invention;
[0016] FIG. 2 is a perspective view showing an embodiment of a head
cover of an internal combustion engine according to the present
invention;
[0017] FIG. 3 is a plan view showing an embodiment of a head cover
of an internal combustion engine according to the present
invention;
[0018] FIG. 4 is a bottom view showing an embodiment of a head
cover of an internal combustion engine according to the present
invention; and
[0019] FIG. 5 is an enlarged longitudinal cross-sectional view
taken along the line V-V in FIG. 3 showing a head cover of an
internal combustion engine according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Now, a preferred embodiment of a head cover according to the
present invention will be described hereinafter with reference to
FIGS. 1-5.
[0021] A head cover 10 according to this embodiment is used in a
straight four-cylinder engine, and consists of a lid-like member
extending in the direction of cylinder arrangement and made by
molding a resin material such as glass-fiber reinforced polyamide
resin. The head cover 10 is securely fastened to an upper surface
of a cylinder head 50 by means of fastening bolts 13 passed through
corresponding through holes 12 defined in bolt boss portions 11
which are formed at a plurality of locations along an outer
periphery of the head cover 10.
[0022] An intake collection chamber (surge tank) 51 of an engine
intake system is disposed close to an outer surface of a ceiling
wall 14 of the head cover 10. The intake collection chamber 51 of
the engine intake system herein includes an intake collection
chamber of an intake manifold and a surge tank. In FIG. 1, a
reference numeral 52 indicates intake branch pipes for distributing
the intake air from the intake collection chamber 51 to each of the
cylinders (not shown in the drawing) of the internal combustion
engine.
[0023] In a portion of the ceiling wall 14 of the head cover 10,
specifically, in a vicinity of one end of the ceiling wall 14 in a
direction of cylinder arrangement, a boss portion 32 defining an
oil inlet 31 and an oil trap portion 33 surrounding the boss
portion 32 are formed, where the boss portion 32 is adapted such
that an oil filler cap can be detachably attached to the boss
portion 32. An outer boundary of the oil trap portion 33 is defined
by an oil outflow prevention wall 34 extending upright from the
ceiling wall 14. A part of the oil outflow prevention wall 34 is
broken to form an oil discharge opening 35. The oil discharge
opening 35 opens toward one lateral direction (right in FIG. 1)
with respect to the direction of cylinder arrangement so that the
oil would not splash on a driving belt disposed on a frontal side
of the engine.
[0024] Attached to an inner side of the ceiling wall 14 of the head
cover 10 (specifically, on an inner side of a later-described
concave ceiling wall 20) is a breather chamber partition plate 15.
The head cover 10 defines a breather chamber 16 between the ceiling
wall 14 and the breather chamber partition plate 15. The breather
chamber 16 constitutes a passage space that may be also referred to
as an oil separator chamber, and has a rectangular cross-section
that is elongated in a lateral direction (left and right direction
in FIG. 1) to achieve a sufficient inner volume of the breather
chamber 16 while maintaining a small passage height (chamber
height) of the breather chamber 16.
[0025] The passage height of the breather chamber 16 is designed to
increase in both lateral directions from a lateral center of the
breather chamber 16, and this contributes to ensuring a sufficient
inner volume of the breather chamber 16 and suppressing the flow
resistance of the blow-by gas. As shown in FIG. 5, the breather
chamber partition plate 15 is formed with a plurality of relief
portions 15B corresponding to the number of the cylinders in order
to avoid interfering with the valve mechanism (not shown in the
drawings) mounted on the cylinder head 50. The relief portions 15B
are formed by depressing prescribed portions of the breather
chamber partition plate 15 that oppose the valve mechanism toward
the breather chamber 16. Thus, the relief portions 15B protrude
into the breather chamber 16. In this connection, the ceiling wall
14 of the head cover 10 is formed with relief portions 20A at
portions aligned with the relief portions 15B to avoid interference
with the relief portions 15B. The relief portions 20A each have a
generally semi-spherical shape, and are concave on the inner side
of the ceiling wall 14 (or when seen from the breather chamber 16
side) and convex on the outer side of the ceiling wall 14.
[0026] A number of small oil passage holes 23 are formed in a
portion of the breather chamber partition plate 15 aligned with the
oil inlet 31.
[0027] The blow-by gas enters the breather chamber 16 from blow-by
gas inlets 17A, 17B that open on the inner side of the head cover
10, and the blow-by gas flows through the breather chamber 16 to be
discharged to an outside of the breather chamber 16 through a
blow-by gas outlet port 18 formed in the head cover 10. While the
blow-by gas flows through the breather chamber 16, the oil
component such as oil mist contained in the blow-by gas is
separated and removed from the blow-by gas. The oil separated in
the breather chamber 16 drops to the cylinder head 50 via an oil
drain 17C and the blow-by gas inlet 17A, and is recovered. The
blow-by gas inlet 17A serves both as a blow-by gas inlet and as an
oil drain.
[0028] It should be noted that a space defined between the oil
inlet 31 and the oil through holes 23 is separated from the
breather chamber 16 by a partition wall 20C.
[0029] In order to enhance the oil mist separating ability of the
breather chamber 16, a plurality of baffle walls 19 are formed
alternately on the inner surface of the ceiling wall 14. Each
baffle wall 19 has a double wall structure comprising a pair of
walls, between which a recessed groove 19A opening toward the
breather chamber partition plate 15 is defined. On portions of the
breather chamber partition plate 15 that oppose the baffle walls
19, baffle walls 15A are protrudingly formed. The baffle walls 15A
protrude into the corresponding recessed grooves 19A and, in
cooperation with the baffle walls 19, form a labyrinth-like
structure within the breather chamber 16.
[0030] It should be noted that the baffle wall 15A opposing the
relief portion 20A is formed on the associated relief portion 15B,
and the baffle wall 19 opposing the relief portion 15B is formed on
the associated relief portion 20A. The baffle wall 19 formed on the
relief portion 20A is provided with such a shape that can avoid
interference with the associated relief portion 15B (see FIG.
5).
[0031] The above baffle walls 19, 15A form a labyrinth-like blow-by
gas passage in the breather chamber 16, thereby increasing the
travel distance of the blow-by gas within the breather chamber 16.
This can improve the oil mist separation effect of the breather
chamber 16.
[0032] As described above, the breather chamber 16 is defined on
the inner side of the portion of the ceiling wall 14 of the head
cover 10 that opposes the intake collection chamber 51, and the
cross-section of the breather chamber 16 has a shape elongated in
the lateral direction (left and right direction in FIG. 1) in order
to ensure a sufficient inner volume of the breather chamber 16
while maintaining a small passage height of the breather chamber
16.
[0033] The portion of the ceiling wall 14 opposing the intake
collection chamber 51 is constituted by a concave ceiling wall 20
that defines a concave surface facing the intake collection chamber
51. The shape of the concave surface of the concave ceiling wall 20
is designed so as to extend substantially along an outer profile of
the intake collection chamber 51 opposing the concave ceiling wall
20. In this embodiment, the intake collection chamber 51 has a
cylindrical outer profile (i.e., circular lateral cross-section),
and thus the concave shape of the concave ceiling wall 20 is
constituted by an arcuate surface extending substantially along the
cylindrical outer profile of the intake collection chamber 51.
[0034] The cylindrical outer profile (circular lateral
cross-section) of the intake collection chamber 51 contributes to a
higher rigidity of the intake collection chamber 51. With the
concave ceiling wall 20, the head cover 10 of the present
embodiment can easily cope with the intake collection chamber 51
having the cylindrical outer profile and with high rigidity. It
should be mentioned that the lateral cross-section of the intake
collection chamber 51 may not be limited to a circle, but may be a
substantially circular shape such as an ellipse or an oblong
circle. In the cases that the intake collection chamber 51 has a
substantially circular lateral cross section also, the intake
collection chamber 51 can assume a high rigidity, and the head
cover of the present invention can easily cope with such an intake
collection chamber 51.
[0035] The concave ceiling wall 20 is further formed with a
recessed groove 21 serving as a recess that recedes toward the
inner side of the head cover 10. The recessed groove 21 consists of
a narrow recessed groove extending in the crankshaft direction of
the internal combustion engine (left and right direction in FIGS. 2
and 3) or in the direction of cylinder arrangement at a lowermost
portion of the concave surface of the concave ceiling wall 20
(i.e., at a position at which the concave ceiling wall 20 is
laterally divided into halves). The recessed groove 21 is connected
to the oil trap portion 33 at its one end 21A in the cylinder
arrangement direction. It should be noted that the oil outflow
prevention wall 34 is partly broken at a position between the oil
trap portion 33 and the recessed groove 21 so that the recessed
groove 21 is connected to the oil trap portion 33.
[0036] Further, a grid-shaped ribs 22 are integrally molded
(formed) on a substantially entire part of the inner surface of the
concave ceiling wall 20.
[0037] As described above, because the part of the ceiling wall 14
of the head cover 10 opposing the intake collection chamber 51 is
constituted by the concave ceiling wall 20, this part of the
ceiling wall 14 (i.e., the concave ceiling wall 20) can assume a
rigidity comparable to that of a circular pipe, and thus is less
likely to undergo panel resonance due to vibrations generated by
the valve mechanism or the like on the engine main body side.
[0038] Further, because the narrow recessed groove 21 extending
along the cylinder arrangement direction is formed at the lowermost
portion of the concave surface of the concave ceiling wall 20, an
area of the concave ceiling wall 20 that could undergo panel
resonance is reduced, and side walls 21B, 21C of the recessed
groove 21 can serve as reinforcing ribs. These can contribute to
making the concave ceiling wall 20 less likely to undergo panel
resonance.
[0039] Further, because the grid-shaped ribs 22 are formed over a
substantially entire part of the inner surface of the concave
ceiling wall 20, the area of the concave ceiling wall that could
undergo panel resonance can be reduced even further, and this makes
it even harder for the concave ceiling wall 20 to undergo panel
resonance.
[0040] Still further, the concave ceiling wall 20 is formed with
the substantially semi-spherical relief portions 20A at a plurality
of longitudinal positions on the head cover 10 (in this embodiment,
four positions corresponding to the number of the engine
cylinders), and this also increases the panel rigidity of the
concave ceiling wall 20 and thus contributes to preventing panel
resonance of the ceiling wall 20. Further, each relief portion 20A
forms a recess in the breather chamber 16, thus contributing to
ensure a sufficient inner volume of the breather chamber 16.
[0041] Owing to the above features, the panel rigidity of the
ceiling wall 14 of the head cover 10 is improved, and it is
possible to ensure a sufficient volume of the breather chamber 16
and achieve a satisfactory NVH performance while coping with a
design change or volume increase of the intake collection chamber
51 of the engine intake system disposed above the head cover
10.
[0042] Because the recessed groove 21 is connected to the oil trap
portion 33 formed around the boss portion 32 that defines the oil
inlet 31, the rainwater or muddy splashes accumulated in the
recessed groove 21 will flow to the oil trap portion 33 and be
readily discharged from the oil discharge opening 35 to the outside
of the head cover 10.
[0043] Therefore, it is possible to prevent the rainwater or muddy
splashes from staying in the recessed groove 21, and thus avoid
deterioration of the head cover 10 made of resin due to chemical
components or the like contained in the rainwater or muddy
splashes.
[0044] The beneficial effects of the present embodiment can be
summarized as follows:
[0045] (1) Because the part of the ceiling wall of the breather
chamber 16 that corresponds to the intake collection chamber 51 is
constituted by the concave ceiling wall 20, it is possible to
reduce the height of the head cover 10 so that the head cover does
not interfere with the intake collection chamber 51, while
achieving a necessary volume of the breather chamber 16. Further,
because the concave ceiling wall 20 is formed with the recessed
groove 21 that further recedes toward the inner side of the head
cover 10, it is possible to improve the panel rigidity of the
concave ceiling wall 20 and prevent deterioration of NVH
performance.
[0046] If the ceiling wall of the head cover 10 has a shape as
shown by phantom line P in FIG. 1, the ceiling wall could have a
high rigidity, but in order to avoid interference, the intake
collection chamber 51 would have to be made smaller as shown by
phantom line D in FIG. 1. However, according to the present
embodiment, it requires only a simple design change of the head
cover 10 as described above to ensure a sufficient volume of the
breather chamber 16 and achieve a satisfactory NVH performance
while coping with a design change or volume increase of the intake
collection chamber 51 of the engine intake system disposed above
the head cover.
[0047] (2) By adapting the concave surface of the concave ceiling
wall 20 so as to extend substantially along the outer profile of
the intake collection chamber 51 that opposes the concave ceiling
wall 20, it is possible to prevent interference between the ceiling
wall and the intake collection chamber 51 while ensuring a
sufficient breather chamber volume.
[0048] (3) By forming a recessed groove 21 at the lowermost portion
of the concave ceiling wall 20, an area of the ceiling surface
(vibration surface) can be evenly reduced by the recessed groove
21, and therefore an anti-vibration and noise performance can be
improved.
[0049] (4) If the recessed groove 21 consists of a recessed groove
extending substantially in the crankshaft direction, the ceiling
surface is divided along the crankshaft direction which is a
longitudinal direction of the head cover 10. As a result, the area
of vibration surface can be considerably reduced and this improves
the anti-vibration and noise performance.
[0050] (5) By connecting the recessed groove 21 to the oil trap
portion 33 formed around the oil inlet boss portion 32, it is
possible to discharge the water or the like in the recessed groove
21 from the oil discharge opening 35 to an exterior of the head
cover 10, and prevent early deterioration of the head cover 10 made
of resin.
[0051] (6) When the grid-shaped ribs 22 are formed on the inner
side of the concave ceiling wall 20, the ribs 22 and the recessed
groove 21 partition the concave ceiling wall 20 (or vibration
surface) into parts, and this reduces the area of the vibration
surface to thereby improve the anti-vibration and noise
performance.
[0052] It should be mentioned that the recessed groove 21 does not
necessarily extend along the crankshaft direction, but may extend
in a direction perpendicular to the crankshaft direction. Further,
the recessed groove 21 does not have to be continuous in the
crankshaft direction but may comprise a plurality of discrete
recesses. The recess or recessed groove may not be provided at the
lowermost position of the concave ceiling wall 20 and a plurality
of recesses or recessed grooves may be formed in the concave
ceiling wall 20. The concave shape of the concave ceiling wall 20
is not limited to an arcuate shape but may be of V-shape formed by
inclined surfaces.
[0053] The disclosure of the original Japanese patent application
(Japanese Patent Application No. 2007-130263 filed on May 16, 2007)
on which the Paris Convention priority claim is made for the
present application is hereby incorporated by reference in its
entirety.
* * * * *